Electronic Telegram No. 5142 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network AU CANUM VENATICORUM R. Schmidt, Burleith Observatory, Washington, DC, reports the following mean I_c magnitudes for the blazar AU CVn = B2 1308+326 obtained with a 0.32-m PlaneWave CDK telescope from 180-s CCD exposures: June 25.105 UT, 12.86; 26.103, 12.72; 28.102, 12.34. This object is undergoing its brightest outburst in forty years (cf. http://www.astronomerstelegram.org/?read=15474). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 June 29 (CBET 5142) Daniel W. E. Green